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No. 615,094. Patented Nov. 29, I898.

J. MGKECHNIE.

SCREW PROPELLER.

(Application filed Dec. 27, 1 897.) (No Model.) 3 Sheets-Sheet I.

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No. -6l5,094. Patented Nov. 29, I898 J. MCKECHNIE SCREW PROPELLER.

(Application flied Dec. 27, 1897.) I (No Model.) 3 Sheets-Sheet Z.

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No. 615,094. Patented Nov. 29, I898.

J. McKECHNlE.

SCREW PROPELLEB.

(Application filed Dec. 27, 1897) (No Model. 3 Sheets-Sheet 3.

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FFICE.

PATENT JOHN MOKEOHNIE, OF GLASGOW, SCOTLAND.

SCREW-PROPELLER.

SIFECIFICATION forming part of Letters Patent No. 615,094, dated November 29, 1898.

Application filed December 27, 1897. Serial No. 663,609. (No model.)

To all whom it may concern.-

Be it known that I, JOHN MOKEOHNIE, engineer, of 17 Oswald street, in the city of Glasgow, Scotland, have invented certain new and useful Improvements in Screw-Propellers, (which have been patented in Great Britain by Letters Patent dated May 11, 1897, No. 11,378,) of which the following is a specification.

This invention, which relates to screw-propellers, consists in casting or fixing upon the boss or between the blades of a screw-propeller one or more projections, collars, or rings.

The invention is illustrated by the accompanying drawings.

Figure 1 is an end elevation, and Fig. 2 a plan, of the propeller in which the collar is cast integral with the propeller; and Figs. 3 and 4 are views corresponding, respectively,to Figs. 1 and 2, showing the ring or collar made in several parts bolted to the boss of the propeller. Figs. 5 and 6 are similar views of the propeller as fitted or formed with three rings or collars.

In carrying out the invention I form the collar or ring A upon the propeller-boss B and extending between the blades O. The collar or ring may be of any shape or form in cross section, but is preferably made conical and may be cast upon and form part of the propeller, as shown at Figs. 1 and 2, or it may be fitted and fixed upon either the boss, as shown at Figs. 3 and 4, or secured to the blades by any form of attachment.

As shown at Figs. 5 and 6, three collars or rings A or a greater or less number may be formed or fitted on the propeller-boss, and when there are two or more such collars or rings orifices, such as a, are formed in the propeller-blades near the boss to permit of the passage of the water.

The rings or collars near each end of the boss may take the form of face-plates attached to the ends of the boss and may be perforated.

As is well known, there is at the stern of a ship a following wave or stream which travels practically at the same speed as the vessel, and it is in this stream that the propeller rotates. The stream tends to fall behind the propeller and would thus become a drag on the vessel. That objection may be obviated by making the propeller with a very large central boss, which brings the following wave close up to the propeller; but the large boss has the further objection of offering a large frictional surface in its rotation through the water and of being extremely heavy. The provision of disks, rings, or collars attached to the propeller in the manner described has the effect of increasing the efiective diameter of the boss, so as to produce the well-known efiect of bringing forward the following Wave, and thus lessening the retardation of the vessel without having recourse to the use of a heavy and cumbrous boss.

Having now described the invention, what I claim, and desire to secure by Letters Patent, is

1. A propeller having screw-blades of ordinary form, in combination with a collar or ring or like projections formed or fitted on the boss and extending between the blades, substantially as set forth.

2. A screw-propeller having a number of collars or rings or like projections formed or fitted on the boss and extending between the blades of the propeller substantially as set forth.

Signed at Glasgow, Scotland, this 13th day of December, 1897.

JOHN MOKEOHNIE.

Witnesses:

WALLACE FAIRWEATHER, JNo. ARMSTRONG, J unr. 

